I am not sure if that currently is or will continue to be true. It has been
true in the past.
The Feds publish the Manual of Uniform Traffic Control Devices (MUTCD) and
Standard Highway Signs & Markers (SHSM). In many cases, a choice is offered,
and the States may choose which of the allowable choices they will use, and
usually have their own laws uniformly applying that choice to the State. (The
above are available online as pdf files). There is a process for the Feds to
"bless" choices not in the book, but it is a PITA. It is used mostly to test
new sign ideas. If they are good ideas, they make it into a later edition.
Past editions came in metric and english versions (these refer to sign
dimensions, both books allowed english or metric message content). The States
have generally opposed highway metrication and the metric book and metric sign
content was not much used. The 2009 MUTCD was issued with ALL metric content
moved to an appendix. In my view, it would be VERY difficult to determine what
in the appendix applies to what sign and to design metric highway marking from
the poor direction given therein. (Easiest way would be to work from a past
edition and check for changes). The companion SHSM is usually a year later and
has not been issued yet. I suspect the next edition of MUTCD will remove the
metric appendix and we will never see a new sign with either metric dimensions
or content unless we drive to Canada or Mexico.
It appears to be unconditional surrender of the FHWA to the "forces of evil" re
metrication. Status of metric has gone from "fully approved by the Feds if the
State chooses it", to "difficult and debatable", and will probably become "not
a choice." If it goes to the latter, a State could still appeal for "special
approval" but I see that in the set {snowball, hell}.
________________________________
From: "[email protected]" <[email protected]>
To: U.S. Metric Association <[email protected]>
Cc: U.S. Metric Association <[email protected]>
Sent: Fri, June 11, 2010 12:31:35 AM
Subject: [USMA:47689] RE: Are metric speed limit and/or distance signs
permitted by US Federal law or regulation?
They are legal...but states have chosen not to use them...except in certain
circumstances.
-------- Original Message --------
>Subject: [USMA:47688] Are metric speed limit and/or distance signs
>permitted by US Federal law or regulation?
>From: [email protected]
>Date: Thu, June 10, 2010 9:18 pm
>To: "U.S. Metric Association" <[email protected]>
>
>
>All:
>
>I just realized I am not clear about the legal status of metric distance and
>speed limit signs in the USA.
>
>Do Federal laws and regulations permit them in all circumstances? Only some?
>
>What role do state, county, and local laws and regulations play in all this?
>
>I ask because I'm wondering if turns out to be the case that the UK is the
>only country on the planet that has officially outlawed metric distance and
>road signs on officially maintained roadways. Even though such signs are
>virtually non-existent here in the USA, I'm presuming this is so simply
>because the states have chosen not to use them rather than because they have
>been made illegal either at the Federal or the state level.
>
>Thanks,
>Ezra
>
